Pump-motor assembly

ABSTRACT

A pump-motor assembly includes a motor housing, a motor disposed substantially within the motor housing, and a pumping element driven by the motor. A pressurized region is filled with a fluid pressurized by the pumping element, and a fluid passage is in fluid communication with the pressurized region and the motor housing. Fluid flows from the pressurized region to the motor housing and at least partially submerges the motor.

TECHNICAL FIELD

This disclosure relates to pumps driven by electric machines.

BACKGROUND

Pumps are devices used to move fluids, such as liquids, gases or slurries. Vehicles may use pumps in transmissions to provide pressurized oil for engagement and disengagement of clutches and other components within the transmission. Pumps may be driven with power from mechanical sources within the vehicle (such as the crankshaft) or by electric machines, directly or indirectly.

SUMMARY

A pump-motor assembly is provided. The pump-motor assembly includes a motor housing, a motor disposed substantially within the motor housing, and a pumping element driven by the motor. A pressurized region is filled with a fluid pressurized by the pumping element, and a fluid passage is in fluid communication with the pressurized region and the motor housing. Therefore, the fluid flows from the pressurized region to the motor housing and at least partially submerges the motor.

The above features and advantages, and other features and advantages, of the present invention are readily apparent from the following detailed description of some of the best modes and other embodiments for carrying out the invention, as defined in the appended claims, when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, isometric view of a pump-motor assembly, showing some of the interior components in phantom;

FIG. 2 is a schematic, cross-sectional view of the pump-motor assembly shown in FIG. 1, taken along a line 2-2 of FIG. 1;

FIG. 3 is a schematic, cross-sectional view of a pump-motor assembly similar to that shown in FIG. 1, cross-sectioned along a line similar to the line 2-2 of FIG. 1;

FIG. 4 is a schematic, cross-sectional view of another pump-motor assembly similar to that shown in FIG. 1, cross-sectioned along a line similar to the line 2-2 of FIG. 1; and

FIG. 5 is a schematic, cross-sectional view of another pump-motor assembly similar to that shown in FIG. 1, cross-sectioned along a line similar to the line 2-2 of FIG. 1.

DETAILED DESCRIPTION

Referring to the drawings, wherein like reference numbers correspond to like or similar components whenever possible throughout the several figures, there is shown in FIG. 1 and FIG. 2 two schematic views of a pump-motor assembly 10. FIG. 1 shows a partial, isometric view of the pump-motor assembly 10 and FIG. 2 shows a cross-sectional view of the pump-motor assembly 10 taken along line 2-2 of FIG. 1. Some components of the pump-motor assembly 10 are shown in phantom in FIG. 1. Features and components shown in other figures may be incorporated and used with those shown in FIGS. 1-2.

While the present invention is described in detail with respect to automotive applications, those skilled in the art will recognize the broader applicability of the invention. Those having ordinary skill in the art will recognize that terms such as “above,” “below,” “upward,” “downward,” et cetera, are used descriptively of the figures, and do not represent limitations on the scope of the invention, as defined by the appended claims.

The pump-motor assembly 10 includes, generally, two different components or sides: a pumping side 12 and motor side 14. The pumping side 12 pressurizes (pumps) a working fluid, such as automatic transmission fluid (ATF) or oil. The fluid is brought into the pumping side 12 at relatively low pressure through an inlet port (not shown) and transfers the pressurized fluid through a pump outlet 16 to another component or assembly using the pressurized fluid. The location of the inlet and outlet are not limiting. The pumping side 12 receives power from the motor side 14, which may be referred to as an electric motor.

A pumping element 18 (not shown in FIG. 1, viewable in FIG. 2) rotates under power of the motor side 14 to pressurize the fluid and move it toward the pump outlet 16. The pump-motor assembly 10 and the pumping element 18 may be any one of several types of pumps and there may be additional components (such as idlers) involved in the pumping process. The pumping element 18 and, therefore, pump-motor assembly 10 type may be, without limitation: gerotor (which is shown, but only viewable in FIG. 2); external gear; roots-type; screw; variable-vane; centrifugal; or other rotating pump types.

The motor side 14 includes a motor 20 disposed substantially within a motor housing 22. The motor 20 drives the pumping element 18, directly or indirectly. The motor 20 includes a rotor 24 and a stator 26 (both of which are hidden from view by the motor housing 22 and are schematically shown with phantom lines in FIG. 1). Electric energy is converted into kinetic energy by the rotor 24 and the stator 26, causing the motor 20 to rotate.

The kinetic energy of the motor 20 is then converted into pressure by the pumping element 18. A pressurized region 28 of the pumping side 12 is filled with the fluid pressurized by the pumping element 18, and is in fluid communication with the pump outlet 16. A fluid passage 30 (hidden from view in FIG. 1, viewable in FIG. 2), which may take different forms, is in fluid communication with the pressurized region 28 and the motor housing 22, such that the fluid flows from the pressurized region 28 to the motor housing 22 and at least partially submerges the motor 20.

The pressurized region 28 represents any area capable of moving fluid away therefrom and may be defined by a cavity within the pumping side 12. As the pumping element 18 works to pressurize fluid, the pressurized region 28 is filled (continuously, during steady-state operation) with pressurized fluid that may then be moved through the fluid passage 30 to the motor housing 22.

A transfer shaft 34 (hidden from view in FIG. 1, viewable in FIG. 2) is configured to transfer power between the motor 20 and the pumping element 18. In the configuration shown in FIGS. 1-2, the transfer shaft 34 is connected to the rotor 24. The fluid passage 30 is adjacent to the transfer shaft 34, such that the fluid passage 30 is generally centered relative to the motor 20.

As shown in FIG. 2, the pump-motor assembly 10 includes a bushing 36 that is configured to carry the transfer shaft 34. The bushing 36 may be formed from, for example and without limitation: bronze, graphite, plastic, ceramic, or another suitable material. In the pump-motor assembly 10 shown in FIGS. 1-2, the fluid passage 30 is incorporated into the bushing 36. Therefore, instead of sealing against the flow of fluid past the bushing 36, the bushing 36 allows fluid to move from the pressurized region 28 of the pumping side 12 to the motor housing 22 of the motor side 14.

The pump-motor assembly 10 may be configured such that the fluid flows from the pressurized region 28 to the motor housing 22 at a first flow rate, which is substantially constant over the normal operating conditions of the pump-motor assembly 10. The first flow rate may vary depending upon, for example and without limitation, the size of the pump-motor assembly 10, the size of the motor 20, or the volume of fluid being pumped by the pump-motor assembly 10. Depending on the needs of the pump-motor assembly 10, the first flow rate may be very low, such that fluid is trickling or leaking through the fluid passage 30 into the motor housing 22. Because the fluid passage 30 is located adjacent to the center of the pumping element 18 adjacent the transfer shaft 34, the pressure at the fluid passage 30 may be relatively low compared to areas radially distant from the transfer shaft 34.

To maintain control of the level of fluid submerging the motor 20, at least one exit port 46 is formed in the motor housing 22. The exit port 46 is located to allow the fluid to form a pool in the motor housing 22. Therefore, relative to gravity and depending upon the mounting location of the pump-motor assembly 10 in, for example, a vehicle (not shown), the exit port 46 will be located above the bottom of the motor housing 22. The exit port 46 may be located above (relative to gravity) the axis of the transfer shaft 34.

FIG. 1 shows two highly-illustrative fluid levels. A first level 50 illustrates the surface of the fluid pooling in the motor housing 22 when the pump-motor assembly 10 is level or at an approximately zero-degree grade angle. A second level 51 illustrates the surface of the fluid pooling in the motor housing 22 when the pump-motor assembly 10 is at an approximately thirty-degree grade angle.

Note that the pump-motor assembly 10 may be mounted into the vehicle at an angle, such the second level 51 is representative of the state of the pump-motor assembly 10 when the vehicle is actually at zero grade. Note also that a portion of the stator 26 and rotor 24 remain in contact with the fluid pool even when the pump-motor assembly is at an angle.

The fluid in the motor housing 22 cools the rotor 24 and stator 26 of the motor 20 and lubricates one or more bearings (if present) 39. The controlled entrance of fluid into the motor side 14 from the pressurized region 28 of the pumping side 12 may improve performance over bringing fluid from other sources, such as an oil sump (not shown). Location of the exit port 46 ensures that sufficient fluid levels are maintained in the motor housing 22 during all operating conditions of the vehicle. The rotor 24 may be supported by rolling bearings 39, which may be any suitable bearing.

The fluid provided by the fluid passage 30 lubricates the bearings carrying the rotor 24 and may reduce drag on the motor 20 by eliminating the need for bearing grease. Cooling the motor 20 with fluid from the pumping side 12 may allow the motor 20 to be reduced in size relative to externally-cooled electric motors which may be used for the same pumping element 18.

Referring now to FIG. 3, and with continued reference to FIGS. 1-2, there is a pump-motor assembly 110, which may be similar or may be used similarly to the pump-motor assembly 10 shown in FIGS. 1-2. The pump-motor assembly 110 is shown in a cross-sectional view taken along a line similar to the line 2-2 of FIG. 1. Features and components shown in other figures may be incorporated and used with those shown in FIG. 3.

The pump-motor assembly 110 includes a pumping side 112 and motor side 114. The pumping side 112 pressurizes (pumps) a working fluid through a pump outlet (not shown) to another component or assembly using the pressurized fluid. The pumping side 112 receives power from the motor side 114. A pumping element 118 rotates under power of the motor side 114 to pressurize the fluid and move it toward the pump outlet.

The motor side 114 includes a motor 120 disposed substantially within a motor housing 122. The motor 120 includes a rotor 124 and a stator 126. The kinetic energy of the motor 120 is converted into pressure by the pumping element 118. A pressurized region 128 of the pumping side 112 is filled with the fluid pressurized by the pumping element 118. A fluid passage 130 is in fluid communication with the pressurized region 128 and the motor housing 122, such that the fluid flows from the pressurized region 128 to the motor housing 122 and at least partially submerges the motor 120.

A transfer shaft 134 is configured to transfer power between the motor 120 and the pumping element 118. The fluid passage 130 is adjacent to the transfer shaft 134, such that the fluid passage 130 is generally centered relative to the motor 120.

A bearing 138 is configured to carry the transfer shaft 134. In some configurations of the pump-motor assembly 110, a shaft seal (not shown) surrounds the transfer shaft 134. The shaft seal and the bearing 138 combine to perform a similar function as the bushing 36 shown in FIGS. 1-2. In the pump-motor assembly 110, the fluid passage 130 is incorporated into the bearing 138 and, if present, the shaft seal, such that fluid can pass from the pump side 112 to the motor housing 122 around the transfer shaft 134 past the bearing 138.

An exit port 146 is formed in the motor housing 122. The exit port 146 is configured to allow the fluid to form a pool in the motor housing 122 and at least partially submerge the motor 120. The exit port 146 may be located above or below (relative to gravity) the axis of the transfer shaft 134.

The exit port 146 includes a restrictor 148 disposed therein. The restrictor 148 limits the flow of fluid from the motor housing 122 by either throttling the exit port 146 or selectively opening only when the pressure exceeds a threshold. Therefore, the restrictor 148 limits an exit flow rate from the motor housing 122, such that fluid pressure builds in the motor housing 122. The fluid pressure in the motor housing 122 also provides back pressure against the fluid passage 130, such that additional flow through the fluid passage 130 is limited or throttled if sufficient pressure already exists in the motor housing 122.

Referring now to FIG. 4, and with continued reference to FIGS. 1-3, there is a pump-motor assembly 210, which may be similar or may be used similarly to the pump-motor assembly 10 shown in FIGS. 1-2. The pump-motor assembly 210 is shown in a cross-sectional view taken along a line similar to the line 2-2 of FIG. 1. Features and components shown in other figures may be incorporated and used with those shown in FIG. 4.

The pump-motor assembly 210 includes a pumping side 212 and motor side 214. The pumping side 212 pressurizes (pumps) a working fluid through a pump outlet (not shown) to another component or assembly using the pressurized fluid. The pumping side 212 receives power from the motor side 214. A pumping element 218 rotates under power of the motor side 214 to pressurize the fluid and move it toward the pump outlet.

The motor side 214 includes a motor 220 disposed substantially within a motor housing 222. The motor 220 includes a rotor 224 and a stator 226. The kinetic energy of the motor 220 is converted into pressure by the pumping element 218. A pressurized region 228 of the pumping side 212 is filled with the fluid pressurized by the pumping element 218.

A fluid passage 230 is in fluid communication with the pressurized region 228 and the motor housing 222, such that the fluid flows from the pressurized region 228 to the motor housing 222 and at least partially submerges the motor 220. The pressure of fluid in the pressurized region 228 and the shape of the fluid passage 230 result in an inlet flow pressure at which fluid enters the motor housing 222.

A transfer shaft 234 is configured to transfer power between the motor 220 and the pumping element 218. A bearing 238 is configured to carry the transfer shaft 234 and a shaft seal 240 surrounds the transfer shaft 234. However, unlike the shaft seal of FIG. 3, the shaft seal 240 seals against any passage of fluid around the transfer shaft 234.

The pump-motor assembly 210 includes an orifice 242, which is disposed away from, or non-adjacent to, the transfer shaft 234. The fluid passage 230 is incorporated into the orifice 242. Therefore, the fluid passage 230 is not centered relative to the motor 220. The orifice 242 is located to draw fluid directly from the pressurized region 228.

An exit port 246 is formed in the motor housing 222. The exit port 246 is configured to allow the fluid to form a pool in the motor housing 222 and at least partially submerge the motor 220. The exit port 246 may be located above or below (relative to gravity) the axis of the transfer shaft 234. In the embodiment shown, the exit port 246 is generally central, relative to gravity.

The exit port 246 includes a restrictor 248 disposed therein. The restrictor 248 may be any element that limits the flow of fluid from the motor housing 222 by either throttling the exit port 246 or selectively opening only when the pressure exceeds a threshold. The restrictor 248 limits an exit flow pressure from the motor housing 222, such that fluid pressure builds in the motor housing 222. The fluid pressure in the motor housing 222 also provides back pressure against the fluid passage 230 and the orifice 242, such that additional flow through the fluid passage 230 is limited or throttled if sufficient pressure already exists in the motor housing 222. Therefore, the difference between the exit flow pressure caused by the restrictor 248 and the inlet flow pressure caused by the pressurized region 228 and the fluid passage 230 yields the pressure within the motor housing 222.

Referring now to FIG. 5, and with continued reference to FIGS. 1-4, there is a pump-motor assembly 310, which may be similar or may be used similarly to the pump-motor assembly 10 shown in FIGS. 1-2. The pump-motor assembly 310 is shown in a cross-sectional view taken along a line similar to the line 2-2 of FIG. 1. Features and components shown in other figures may be incorporated and used with those shown in FIG. 5.

The pump-motor assembly 310 includes a pumping side 312 and motor side 314. The pumping side 312 pressurizes (pumps) a working fluid through a pump outlet (not shown) to another component or assembly using the pressurized fluid. The pumping side 312 receives power from the motor side 314. A pumping element 318 rotates under power of the motor side 314 to pressurize the fluid and move it toward the pump outlet.

The motor side 314 includes a motor 320 disposed substantially within a motor housing 322. The motor 320 includes a rotor 324 and a stator 326. The kinetic energy of the motor 320 is converted into pressure by the pumping element 318. A pressurized region 328 of the pumping side 312 is filled with the fluid pressurized by the pumping element 318. A fluid passage 330 is in fluid communication with the pressurized region 328 and the motor housing 322, such that the fluid flows from the pressurized region 328 to the motor housing 322 and at least partially submerges the motor 320.

A transfer shaft 334 is configured to transfer power between the motor 320 and the pumping element 318. A bushing 336 is configured to carry the transfer shaft 334 and also to seal around the transfer shaft 334. Unlike the bushing 36 of FIG. 2, the bushing 336 substantially seals against any passage of fluid around the transfer shaft 334.

The pump-motor assembly 310 includes an orifice 342, which is disposed away from, or non-adjacent to, the transfer shaft 334. The fluid passage 330 is incorporated into the orifice 342. Therefore, the fluid passage 330 is not centered relative to the motor 320. The orifice 342 is located to draw fluid directly from the pressurized region 328.

The orifice 342 includes a bleed valve 344, which provides a proportional flow rate between the pressurized region 328 and the motor housing 322 based upon the pressure of the fluid in the pressurized region 328. As the pressure in the pressurized region 328 increases, more fluid flows through the bleed valve 344 to the motor housing. The bleed valve 344 shown is illustrative only and may represent any component configured to allow increased flow with increased pressure.

The increased fluid flow through the motor 320—as opposed to cooling with oil external to the motor 320—may help to cool the motor 320 during relatively heavy loading of the motor 320. The bleed valve 344 may also be configured to actively vary the flow rate between the pressurized region 328 and the motor housing 322 in response to an electrical or fluidic control signal.

An exit port 346 is formed in the motor housing 322. The exit port 346 is configured to allow the fluid to form a pool in the motor housing 322 and at least partially submerge the motor 320. The exit port 346 may be located above or below (relative to gravity) the axis of the transfer shaft 334.

The detailed description and the drawings or figures are supportive and descriptive of the invention, but the scope of the invention is defined solely by the claims. While some of the best modes and other embodiments for carrying out the claimed invention have been described in detail, various alternative designs and embodiments exist for practicing the invention defined in the appended claims. 

1. A pump-motor assembly, comprising: a motor housing; a motor disposed substantially within the motor housing; a pumping element driven by the motor; a pressurized region filled with a fluid pressurized by the pumping element; and a fluid passage in fluid communication with the pressurized region and the motor housing, such that the fluid flows from the pressurized region to the motor housing and at least partially submerges the motor.
 2. The pump-motor assembly of claim 1, further comprising: a transfer shaft configured to transfer power between the motor and the pumping element; and wherein the fluid passage is adjacent to the transfer shaft.
 3. The pump-motor assembly of claim 2, further comprising: one of a bushing and a bearing configured to carry the transfer shaft; and wherein the fluid passage is incorporated into the one of the bushing and the bearing.
 4. The pump-motor assembly of claim 2, further comprising: a shaft seal disposed about the transfer shaft; and wherein the fluid passage is incorporated into the shaft seal.
 5. The pump-motor assembly of claim 2, further comprising: an orifice disposed non-adjacent to the transfer shaft; and wherein the fluid passage is incorporated into the orifice.
 6. The pump-motor assembly of claim 5, wherein the orifice includes a bleed valve; and wherein the bleed valve provides a proportional flow rate between the pressurized region and the motor housing based upon the pressure of the fluid in the pressurized region.
 7. The pump-motor assembly of claim 6, further comprising: an exit port in the motor housing; and wherein the exit port is located to allow the fluid to form a pool in the motor housing.
 8. The pump-motor assembly of claim 7, further comprising: wherein the fluid flows from the pressurized region to the motor housing with an inlet flow pressure; wherein the exit port includes a restrictor; and wherein the restrictor provides an exit flow pressure which limits flow from the motor housing, such that fluid pressure builds in the motor housing.
 9. A pump-motor assembly, comprising: a motor housing; a motor disposed substantially within the motor housing; a pumping element driven by the motor; a pressurized region filled with a fluid pressurized by the pumping element; a fluid passage in fluid communication with the pressurized region and the motor housing, such that the fluid flows from the pressurized region to the motor housing and at least partially submerges the motor; and an exit port in the motor housing, wherein the exit port is located to allow the fluid to form a pool in the motor housing.
 10. The pump-motor assembly of claim 9, further comprising: a transfer shaft configured to transfer power between the motor and the pumping element; and wherein the fluid passage is adjacent to the transfer shaft.
 11. The pump-motor assembly of claim 10, further comprising: one of a bushing and a bearing configured to carry the transfer shaft; and wherein the fluid passage is incorporated into the one of the bushing and the bearing.
 12. The pump-motor assembly of claim 9, further comprising: an orifice disposed non-adjacent to the transfer shaft; and wherein the fluid passage is incorporated into the orifice. 